Pixelshift - Pixels and Piezos
Pixelshift is often used in industrial cameras and microscopes to improve resolution and overall image quality. Piezo stages are essential for this technique.
The quality testing and inspection industry has high requirements for cameras and microscopes. The higher the resolution of an image, the more details can be examined and thus inspection results improve. Shorter inspection cycles also play a pivotal role. Here, like almost everywhere else, time is money.
The manufacturers of industrial microscopes and integrated cameras constantly update their product lines to meet these demands. But just putting in more powerful image sensors is not enough. More and more microscope cameras also use a technique called Pixelshift. Thanks to this method, standard resolutions of image sensors like, e.g. CMOS, CCD and FPA, can be increased multiple times. The color quality significantly improves as well.
How does Pixelshift work?
The term Pixelshift refers to a process in which an image is shot multiple times. e.g. a probe in microscopy or larger objects in front of an industrial camera for quality inspection. With each shot the lens or image sensor is moved by half or a third of a pixel. On a PC or other computational device, all these images will be merged into one. The result is a crisper image with a resolution multiple times higher than the original one. Resolution increases with the number of individual images – it increases four times with a shift of half a pixel, nine times with a shift of a third of a pixel and so forth. The true color of the images is not impacted by this process. Another benefit is that individual pixel defects are corrected. Overall, the efficiency of the sensor is increased through Pixelshift.
The optimal technological basis for Pixelshift is a piezo stage that shifts the image sensor or lens along the X- and Y-axes rendering multiple shots with microscopic deviations possible in the first place. Only piezo stages and actuators offer the resolutions for the required µm- shifts
An image pixel does not have a standardized size. In cameras pixel sizes can vary. Today’s industrial cameras and microscopes often use larger image sensors with pixel sizes around 5 µm. These larger surfaces offer more light sensitivity and thus provide sharper images and more detailed results. Consumer products usually use smaller pixel sizes but also show more image noise.
Even though the piezo stages have theoretically unlimited resolutions and are able to provide even smaller steps in the nanometer or sub-nanometer range, the capacities of current displays and the computational power of today’s PCs limit working with higher image resolutions.
Piezo stages provide a lot of additional benefits for the Pixelshift technique. It is not just the high resolution and precision. They have fast reaction times up to the microsecond range and an overall step repeatability, stability and reliability that is unmatched by other technologies.
Which piezo systems can be used for Pixelshift?
With a piezo stage, the “shift” can be realized in different ways. The individual models of PXY series by piezosystem jena for example provides precise, highly repeatable movements along an XY- coordinate system and are ideal for the XY-shifting of an image sensor or lens. Tip/Tilt-stages like the models of the PSH series can also be used. They realize the Pixelshift via angle deviations. Depending on the intention and construction method of an industrial microscope or camera, stages like the ScanXY 40 or certain models of the NanoX® series might also qualify.
To achieve high and stable resolutions with a piezo stage, a piezo amplifier with low electrical noise levels is crucial. The lower the noise level, the smaller the step widths that can be reached. This is, of course, not only important for Pixelshift but for all applications in need of micro-, nano- or sub-nanometer steps. piezosystem jena developed a series of piezo controllers with extremely low electrical noise levels. The digital amplifier d-Divepro for example, only has 0,15 mV. With such amplifiers, optimal piezo usage and control are ensured.
You are developing a microscope or camera system and looking for the optimal stage for Pixelshift integration? We support you all the way - from the first idea to the finished product and beyond. You can reach our technical sales team via sales(at)piezojena.com or call +49(0)364166880. To contact our US team, call +15086346688 or write to usa(at)piezojena.com. Alternatively, you can also use our contact form.
A detailed overview of all our piezo actuators and stages as well as Fiber switches, Piezocomposite actuators and electronics you can find here.